Multiple fields of view time of flight sensor

ABSTRACT

In some embodiments, a ToF sensor includes an illumination source module, a transmitter lens module, a receiver lens module, and an integrated circuit that includes a ToF imaging array. The ToF imaging array includes a plurality of SPADs and a plurality of ToF channels coupled to the plurality of SPADs. In a first mode, the ToF imaging array is configured to select a first group of SPADs corresponding to a first FoV. In a second mode, the ToF imaging array is configured to select a second group of SPADs corresponding to a second FoV different than the first FoV.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/728,213, filed Oct. 9, 2017, which application is hereby incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates generally to a photonic device and, inparticular embodiments, to a multiple fields of view time of flightsensor.

BACKGROUND

Photonic devices may be used in a variety of applications, such as, forexample, mobile phones, cameras, and automotive applications. A numberof applications take advantage of photonic systems using photonicsensors to determine a distance to an object. For example, a photonicranging device application may use time of flight (ToF) to determine adistance between a reflective object and the device. In ToF systems, apulse of light is emitted and reflected off an object back to a singlephotonic sensor. The time taken for the light to travel to the objectand be reflected back onto the single photonic sensor may be used todetermine the distance between the object and the device based on theknown speed of light. Typically, the distance measured is to a singlepoint. In other words, the light is emitted, reflected into the object,and then received by the single photonic sensor, and a single distanceis reported. Light detection and ranging (LIDAR), also called LADAR, isan application that uses ToF techniques to detect the presence ofobjects and its associated distance from a source.

A proximity sensor may benefit from ToF techniques. Proximity sensorsdetect the presence of nearby objects without physical contact.

Another application that may benefit from ToF techniques is autofocus(AF) for cameras. There are two types of AF systems: passive AF systemsand active AF systems. A passive AF system performs AF by analyzing theimage captured by the image sensor. Phase detection AF (PDAF) is anexample of a passive AF system. To perform AF, PDAF splits an image intotwo copies and then adjust the focus until both images are in phase(i.e., merge).

An active AF system determines the distance to the object to be focusedon independently from the optical system and then controls the opticalsystem to focus on such object. For example, an active AF system maymeasure the distance to an object by shining a laser or light emittingdiode (LED) light, such as an edge-emitting laser or vertical cavitysurface emitting laser (VCSEL), to the object and then using a singleToF sensor to determine the distance to the object and automaticallyfocus the camera on the object. Relying on a ToF sensor for AF istypically faster than traditional ways of implementing AF, such as PDAF.

SUMMARY

In accordance with an embodiment, a ToF sensor includes an illuminationsource module, a transmitter lens module, a receiver lens module, and anintegrated circuit that includes a ToF imaging array. The ToF imagingarray includes a plurality of SPADs and a plurality of ToF channelscoupled to the plurality of SPADs. In a first mode, the ToF imagingarray is configured to select a first group of SPADs corresponding to afirst FoV. In a second mode, the ToF imaging array is configured toselect a second group of SPADs corresponding to a second FoV differentthan the first FoV.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, in which:

FIGS. 1a and 1b show a camera fields of view (FoV) and a correspondingToF sensor FoV of an exemplary camera system, according to an embodimentof the present invention;

FIGS. 2a and 2b show a wide FoV of a first lens of a dual camera systemand a narrow FoV of a second lens of the dual camera system and acorresponding ToF sensor FoV;

FIG. 3a shows a portion of a dual camera system having a ToF module,which includes a dual illumination module and a ToF sensor, according toan embodiment of the present invention;

FIGS. 3b and 3c show a ToF imaging array having a wide FoV configurationand a narrow FoV configuration, respectively, according to an embodimentof the present invention;

FIG. 3d shows a circuit for driving a dual illumination source,according to an embodiment of the present invention;

FIG. 3e shows a flow chart of an embodiment method of operating a dualcamera system, according to an embodiment of the present invention;

FIG. 4 shows a portion of a dual camera system having a ToF module,which includes a single illumination module and a ToF sensor, accordingto another embodiment of the present invention;

FIG. 5a shows a portion of a dual camera system having a ToF module,which includes a dual illumination module and a ToF sensor, according toyet another embodiment of the present invention;

FIG. 5b shows a corner-weighted FoV, a center-weighted FoV, and acombined, flat FoV of a dual transmitter (TX) lens, according to anembodiment of the present invention;

FIGS. 6a and 6b show the front and back view, respectively, of a mobilephone including a back-facing dual camera module and a ToF sensor,according to an embodiment of the present invention; and

FIG. 7 shows the front view of a mobile phone including a front-facingdual camera module 808 and ToF sensor 814, according to an embodiment ofthe present invention.

Corresponding numerals and symbols in different figures generally referto corresponding parts unless otherwise indicated. The figures are drawnto clearly illustrate the relevant aspects of the preferred embodimentsand are not necessarily drawn to scale. To more clearly illustratecertain embodiments, a letter indicating variations of the samestructure, material, or process step may follow a figure number.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of the presently preferred embodiments arediscussed in detail below. It should be appreciated, however, that thepresent invention provides many applicable inventive concepts that canbe embodied in a wide variety of specific contexts. The specificembodiments discussed are merely illustrative of specific ways to makeand use the invention, and do not limit the scope of the invention.

The present invention will be described with respect to preferredembodiments in a specific context, a multiple fields of view time offlight (ToF) sensor implemented in a camera of a mobile phone and havingautofocus (AF) assist. Embodiments of the present invention may also beimplemented in point and shoot cameras and other types of cameras. Otherembodiments may be implemented in proximity sensors, gesture recognitionsystems, automotive LIDAR, and other applications that may benefit fromdistance ranging and the generation of depth maps.

In an embodiment of the present invention, a ToF sensor having an arrayof photodetectors and a single fixed receiver (RX) lens iselectronically configurable to have multiple fields of view (FoV). TheToF sensor may switch between different FoVs to match a FoV of aparticular selected camera by turning off portions of the array ofphotodetectors. For example, in a dual camera system having a wide FoVcamera and a narrow FoV camera, the full array of photodetectors of theToF sensor is used when using the wide FoV camera while only a portionof the array of photodetectors of the ToF sensor is used when using thenarrow FoV camera.

AF may be accomplished in a variety of ways. A depth map, for example,may be used for AF purposes. A depth map is a map (or matrix) of thedistance between a three-dimensional scene and a viewpoint. Thedetermination of the depth map may be accomplished, for example, with aToF sensor. A depth map may be represented, for example, as a histogramof distances to objects in the scene. A particular scene may bepartitioned into a plurality of portions, with each of the portionshaving respective distances or histograms of distances to respectiveobjects in the respective portions. The depth map information, which mayinclude a single histogram or a plurality of histograms, may be used tofocus the camera on an object of the scene, or an object in a particularportion of the scene.

A depth map may be captured, for example, with a ToF sensor. A ToFsensor may include an array of photodetectors, such as an array ofsingle photon avalanche diodes (SPADs), for detecting photons fromobjects in the scene. Each photodetector, with the aid of a controllerin some cases, may produce a signal corresponding to a distance to anobject using ToF techniques. The information from a plurality ofphotodetectors in the array of photodetectors may be used to generatethe depth map. A receiver (RX) lens may be used to focus the receivedphotons from the scene into the array of SPADs.

AF may be achieved without generating a full depth map. For example, ina single camera system, such as a mobile phone with a single camera, theToF sensor may be placed next (e.g., adjacent) to the camera lens. TheFoV of the ToF sensor may be designed so that it is equivalent to theFoV of the camera. In some embodiments, a user may use touch-to-focus.In other words, the user may select a portion of an image displaying onthe screen of the mobile phone to focus on it. A ToF sensor may be usedto determine the distance to objects in the selected portion of theimage by using a multi-zone approach where photodetectors correspondingto the selected zone are used to detect the distance to objects in theselected zone. For example, FIG. 1a shows camera FoV 102 and FIG. 1bshows a corresponding ToF sensor FoV 122 of an exemplary camera system,according to an embodiment of the present invention. Camera FoV 102 isillustratively divided into 42 zones/portions arranged in an array of 6rows and 7 columns. ToF sensor FoV 122 is similarly arranged. Forexample, a SPAD may be associated with each of the zones, resulting in aToF sensor having 42 SPADs. ToF sensor FoV 122 is equivalent to cameraFoV 102. When a user selects image area portion 104 to focus on it, thephotodetector 124, which in some embodiments may include a plurality ofphotodetectors, may be used to determine the distance to objects in suchcorresponding portion and then provide such information to the AF module(autofocus module). The AF module may then control the lens driver toautomatically focus on such objects.

In some embodiments, a user may use touch-to-focus for selecting aportion of an image displaying on the screen of the mobile phone tofocus on it. In other embodiments, software may be used to automaticallyselect a region of interest to focus on it. For example, a camera focusmay determine an object of interest based on image recognition andselect the region containing such object to focus on it. Otherembodiments may use a combination of touch-to-focus and using softwareto automatically focus on a particular portion of the screen.

It is noted that a 6×7 array with 42 zones is simply one example andother size arrays could alternatively be used.

In some camera systems, such as stereo cameras or dual camera systems,two cameras may be used. In some dual camera systems, such as a dualcamera system in a mobile phone, a first lens may have a wide FoV and asecond lens may have a narrow FoV. The second lens may have, forexample, 2× optical zoom while the first lens may have 1× optical zoom(i.e., no zoom). All else being equal, a camera with a wide FoV covers alarger area than a camera with a narrow FoV, and a camera with a narrowFoV has a higher photon rate than a camera with a wide FoV.

Because of the different FoVs of each of the cameras of the dual camerasystem, it may be difficult to achieve AF with a single ToF sensor. Inother words, AF may be difficult to implement in a dual camera systemhaving a camera with a wide FoV and a camera with a narrow FoV with asingle ToF sensor because the field of view of the single ToF sensor maybe different than the FoV of at least one of the cameras. For example,FIGS. 2a and 2b show wide FoV 204 of a first lens of a dual camerasystem and shows narrow FoV 202 of a second lens of the dual camerasystem, and corresponding ToF sensor FoV 222.

As shown in FIG. 2a , when using the first lens having wide FoV 204, acorresponding portion 226 of ToF sensor FoV 222, which corresponds tothe full array of photodetectors of the ToF sensor, is covered. In otherwords, the FoV of the ToF sensor is equivalent to the FoV of the firstlens. As shown in FIG. 2b , when using the second lens having narrow FoV202, only portion 224 of the array of photodetectors of ToF sensor 222captures relevant information while portion 228, which covers the areabetween portion 226 and 224, does not capture relevant information. Forexample, portion 228 may capture noise resulting from ambient lightentering the ToF sensor.

In the dual camera system just described, AF based on a depth mapgenerated by the full array of photodetectors of the ToF sensor may workimproperly when using the second lens, in part, because of the presenceof noise in portion 228. The operation of the photodetectors in portion228 when using the second lens may also consume unnecessary power, sincethe photodetectors in portion 228 are not collecting information usefulfor AF when using the second lens.

In some embodiments of the present invention, a dual camera system has awide camera, a narrow camera, two light sources and a ToF sensor havingan electronically configurable array of photodetectors. A first lightsource is configured to illuminate a wide FoV equivalent to the FoV ofthe wide camera. A second light source is configured to illuminate anarrow FoV equivalent to the FoV of the narrow camera. The array ofphotodetectors is configurable to have a FoV equivalent to the FoV ofthe wide camera when the wide camera is used and is configurable to havea FoV equivalent to the FoV of the narrow camera when the narrow camerais being used. Using two illumination sources allows for matching theillumination FoV with the FoV of the selected camera.

FIG. 3a shows a portion of dual camera system 400 having ToF module 403,which includes dual illumination module 404 and ToF sensor 402,according to an embodiment of the present invention. Dual camera system400 also includes a wide FoV camera (not shown) and a narrow FoV camera(not shown). Dual illumination module 404 includes dual illuminationsource 406 and dual transmitter (TX) lens 418. Dual illumination source406 includes light source 421 and light source 423. Dual TX lens 418includes wide FoV lens 420 and narrow FoV lens 422. ToF sensor 402includes substrate 405, ToF imaging array 408, and RX lens 416.

During normal operation, ToF module 403 may operate in two differentmodes. In a first mode, the wide FoV camera is selected for use. In thefirst mode, light source 421 may be turned on while keeping light source423 off. The light from light source 421 is projected through wide FoVlens 420 and illuminates wide FoV 424. Objects in wide FoV 424 reflectlight coming from light source 421 into RX lens 416, as illustrated bylight rays 414. Light rays 414 go through RX lens 416 and illuminate thephotodetectors of ToF imaging array 408 surrounded by perimeter 409. Thearray of photodetectors surrounded by perimeter 409 is selected and usedto generate ranging information, such as histograms. As discussed belowwith respect to FIG. 3B, each ToF zone (represented by dotted lines inFIG. 3b ) may generate a histogram. The information generated by thearray of photodetectors selected may be supplied to the AF module toautomatically focus the wide FoV camera on the objects in wide FoV 424.

In a second mode, the narrow FoV camera is selected for use. In thesecond mode, light source 423 may be turned on while keeping lightsource 421 off. The light from light source 423 is projected throughnarrow FoV lens 422 and illuminates narrow FoV 426. Objects in narrowFoV 426 reflect light coming from light source 423 into RX lens 416, asillustrated by light rays 412. Light rays 412 go through RX lens 416 andilluminate the photodetectors of ToF imaging array 408 surrounded byperimeter 410. The array of photodetectors surrounded by perimeter 410is selected and used to generate ranging information, such ashistograms. As discussed below with respect to FIG. 3C, each ToF zone(represented by dotted lines in FIG. 3c ) may generate a histogram. Thephotodetectors of the array of photodetectors that are not surrounded byperimeter 410 may be turned off. The information generated by the arrayof photodetectors selected may be supplied to the AF module toautomatically focus the narrow FoV camera on the objects in narrow FoV426.

Dual illumination source 406 may be implemented in ways known in theart. For example, dual illumination source may be implemented with twoVCSELs that are independently controlled. Other illuminationtechnologies may be used.

Dual illumination source 406 may be configured to provide light having asingle wavelength. In some embodiments, multiple wavelengths may beused. For example, a first VCSEL may provide light with a firstwavelength and a second VCSEL may provide light with a secondwavelength, where the first and the second VCSELs are independentlycontrolled.

Dual illumination source 406 may be implemented in a single package.Alternatively, dual illumination source may be implemented discretely,having a first illumination source on a first package and a secondillumination source on a second package different from the firstpackage. Other implementations are also possible.

Dual TX lens 418 is located between dual illumination source 406 and theobjects to be illuminated. Dual TX lens 418 may be implemented in asingle module having a wide TX lens with a fixed wide FoV and a narrowTX lens with a fixed narrow FoV. The FoV of the wide TX lens may bebetween 60° and 80° diagonal. Other FoVs outside this range may be used.The FoV of the narrow TX lens may be less than the FOV of the wide TXlent, such as, for example, between 10° and 25° diagonal. Other FoVsoutside this range may be used.

In some embodiments, dual TX lens 418 may be implemented with adiscrete, fixed wide FoV lens in a first module and a discrete, fixednarrow FoV lens in a second module separate from the first module. Insome embodiments, one or both of the lenses in dual TX lens 418 may havean adjustable FoV. Other implementations are also possible.

RX lens 416 is typically located between the objects being illuminatedby dual illumination source 406 and ToF imaging array 408. RX lens 416may be a fixed lens with a fixed FoV. In some embodiments, RX lens mayhave an adjustable FoV.

RX lens 416 may be implemented discretely. Alternatively, RX lens 416may be implemented in the same module as dual TX lens 418. For example,RX lens and TX lens may be manufactured separately and then integratedinto the same package. Other implementations are also possible.

RX lens 416 may be implemented without a diffractive optical element(DOE). In some embodiments, RX lens may be implemented with a DOE. Insome embodiments, RX lens 416 may be located next to (adjacent) dual TXlens 418 and next to the lenses of the wide FoV camera and the narrowFoV camera of dual camera system 400. In other words, dual TX lens 418,RX lens 416 and the lenses of the wide FoV camera and the narrow FoVcamera may be located in the same plane and near each other. Forexample, dual TX lens 418, RX lens 416 and the lenses of the wide FoVcamera and the narrow FoV camera may be located less than 10 mm fromeach other. In other embodiments, dual TX lens 418, RX lens 416 and thelenses of the wide FoV camera and the narrow FoV camera may be separatedby more than 1 cm, such as 10 cm, or may not be adjacent to each other.

ToF imaging array 408 has a plurality of photodetectors that may beturned on or off based on an external signal (not shown). ToF imagingarray 408 may supply distance information from all of the photodetectorsof the array or from a selected group of photodetectors for rangeextraction. The distance information may be supplied via a plurality ofanalog ToF channels. In some embodiments, the distance information maybe supplied via a plurality of digital ToF channels. A digitalcommunication protocol, such as SPI, I²C, I²S, or similar may also beused to provide distance information. In some embodiments, the distanceinformation includes a sequence of ToF times. Other ways of representingdistances may be used.

The array of photodetectors of ToF imaging array 408 may be implementedwith an array of SPADs. Other photodetectors may be used.

A controller (not shown) may be used to control ToF module 403. Forexample, the controller may be used to activate or deactivateillumination sources of dual illumination source 406. The controller maybe used to extract information from ToF imaging array 408 as well as tocontrol which photodetectors of ToF imaging array 408 are activated andwhich are deactivated. For example, activation and deactivation ofparticular photodetectors of ToF imaging array 408 may be controlled asshown in co-pending U.S. patent application Ser. No. 15/588,127, whichis hereby incorporated by reference in its entirety. The controller mayalso be used to generate the histogram of distances from the selectedphotodetectors.

The controller may be implemented as a single general purpose controlleror as a single custom controller. In some embodiments, the controllermay be implemented as a group of controller. Other implementations arealso possible.

The array of photodetectors of ToF imaging array 408, and the controllermay all be implemented in the same integrated circuit (IC). For example,an IC may include an array of SPADs used for a ToF imaging array, acircuit for controlling the array of SPADs and the VCSELs and a customcontroller. Alternatively, the array of photodetector, the VCSELs andthe controller and the circuit for controlling the array of SPADs andthe VCSEL may be implemented discretely. Other implementations are alsopossible.

The operational distance of AF using ToF module 403 may depend onparameters, such as the power of the illumination sources, the type ofTX lens used, the sensitivity of the photodetectors, and otherparameters. A typical AF application for a mobile phone may have anoperational range between 0 m and 10 m, for example. Different rangesmay also be achieved. In some embodiments, ToF module 403 may achievesubstantially longer ranges, such as 200 m, which may be advantageous,for example, in automotive LIDAR.

Advantages of some embodiments include that the FoV of the ToF imagingsensor may be configured to match the FoV of a selected camera. Having amatching FoV may result in more accurate AF with either the narrow FoVcamera of the wide FoV camera. By electronically configuring the ToFimaging array (without any mechanical changes), a faster response timemay be obtained when compared with systems that mechanically adjust theFoV of the ToF sensor.

Other advantages of some embodiments include that by using twoillumination sources, the area of interest may be illuminated withoutilluminating other areas, which may result in more accurate AF. Byturning off photodetectors that are not being used, power may be saved.Another advantage of some embodiments include that the higher photonrate associated with the narrow FoV may result in a ToF sensorgenerating distance (e.g. range) measurements faster and/or moreaccurate when operating with a narrow FoV, thereby increasingperformance when using narrow FoV camera.

FIGS. 3b and 3c show ToF imaging array 408 having wide FoV configuration428 and narrow FoV configuration 430, respectively, according to anembodiment of the present invention. ToF imaging array includes a-1 rowsand b-1 columns, for a total of (a-1)*(b-1) photodetector zones. Eachzone, such as, for example, zone Z_(0,0), may include a singlephotodetector or a cluster (e.g. a plurality) of photodetectors. Forexample, some embodiments include 42 zones arranged in an array of 6rows and 7 columns of SPADs. The SPADs may be arranged in asemiconductor substrate of an integrated circuit and may be implementedin a Complementary metal-oxide-semiconductor (CMOS) process, forexample. A higher number of photodetectors or a smaller number ofphotodetectors may also be used. Other arrangements may also be used. Asanother example, some embodiments may include 16 rows and 16 columns ofphotodetectors for a total of 256 photodetectors. Arrays with highernumber of photodetectors, such as 10,000 or more, may be used.

ToF imaging array 408 has a plurality of ToF channels, which are used totransmit distance information to an external circuit or system, such asa controller or an AF module. Each ToF channel may be associated with azone. Each ToF channel may transmit a single distance. In someembodiments, each ToF channel may transmit a plurality of distances,such as a histogram of distances. In some embodiments, each ToF channelmay transmit different amount of information based on the FoVconfiguration selected. For example, each ToF channel may transmit asingle distance when ToF imaging array 408 is configured with a narrowFoV and may transmit multiple distances arranged in a histogram ofdistances when ToF imaging array 408 is configured with a wide FoV. Inother embodiments, each ToF channel transmits the same amount ofinformation regardless of the FoV configuration selected. Theinformation transmitted by the ToF channels may be used for AF. Forexample, the information may be used for touch to focus, where theranging information of the selected zone is used for focusing purposes.In some embodiments, if no zone is selected, the system may default tofocusing to a predetermined zone, such as a zone in the center of theFoV.

Each ToF channel may transmit distance information as a histogram ofdistances. The histogram may be represented, for example, as a set orlist of distances. Each distance may be represented, for example, byarrival times. Other ways to represent and/or transmit distances may beused.

In some embodiments, the number of distances transmitted by each ToFchannel may be reduced (e.g., filtered) in some modes of operation.

As shown in FIG. 3b , ToF imaging array 408 operates m-1 rows and n-1columns of ToF channels, for a total of m×n ToF channels, when wide FoVconfiguration 428 is selected. Each ToF channel includes fourphotodetector zones. For example, ToF channel ToF_(x0,y0) is configuredto transmit a histogram of distances captured by photodetector zonesZ_(0,0), Z_(0,1), Z_(1,0), and Z_(1,1). In some embodiments, each ToFchannel may include a different number of photodetector zones, such as asingle photodetector zone, two zones, three zones, or more than fourzones.

As shown in FIG. 3b , all of the photodetectors of ToF imaging array 408are used when wide FoV configuration 428 is selected. In someembodiments, some of the photodetectors may not be used and may beturned off. Such configuration may be advantageous when the FoV of theToF imaging array when using all of the photodetectors does not matchthe FoV of the wide camera.

As shown in FIG. 3c , ToF imaging array 408 operates p-1 rows and q-1columns of ToF channels, for a total of p×q ToF channels, when narrowFoV configuration 430 is selected. Each ToF channel includes a singlephotodetector zone. For example, ToF channel ToF_(x0,y0) is configuredto transmit a single distance or a histogram of distances captured byphotodetector zone Z_(i,j), where Z_(i,j) denotes a zone at an origin ofthe FoV of the narrow FoV camera. In some embodiments, each ToF channelmay include a different number of photodetector zones, such as twozones, three zones, or more than three zones.

In the particular example illustrated in FIGS. 3b and 3c , when ToFimaging array 408 operates in a first mode (wide FoV configuration 428),an array of 5×3 ToF channels are used to transmit ranging information.When ToF imaging array 408 operates in a second mode (narrow FoVconfiguration 430), an array of 4×4 ToF channels are used to transmitranging information. A different number of ToF channels and differentarrangements of ToF channels may be used. As shown in FIGS. 3b and 3c ,ToF imaging array 408 may be reconfigured to match a particular FoV.

In some embodiments p is equal to m, and q is equal to n. In otherwords, the number of ToF channels used when wide FoV configuration 428is selected is the same as the number of ToF used when narrow FoVconfiguration 430 is selected. Having such configuration may beadvantageous because a controller or AF module receiving the ToFinformation from ToF imaging array 408 does not need to performadditional computations based on how ToF imaging array 408 isconfigured. For example, at a first time, a controller may configure ToFimaging array 408 with wide FoV 428 and process information from the m×nToF channels in a first way. At a second time, the controller mayconfigure ToF imaging array 408 with narrow FoV 430 and processinformation from the same m×n ToF channels in the same first way. Otherembodiments may have p being less than or greater than m, and may have qbeing less than or greater than n.

Dual camera system 400 may also be configured to perform touch-to-focuswith either the wide FoV camera or the narrow FoV camera. For example, aparticular ToF channel associated with a particular zone may be selectedto perform AF while ignoring the information from other ToF channels. Insome embodiments, the photodetectors associated with the unselectedzones are deactivated when performing the distance measurements and AF.

As shown in FIGS. 3b and 3c , ToF imaging array 408 may be configured tohave at least two fields of view. For example, a first FoV equivalent toa wide FoV camera and a second FoV equivalent to a narrow FoV camera.Some embodiments may have a ToF imaging array that is configurable tohave multiple FoVs, such as, for example, three FoV, four FoV, or morethan four FoV. Such a multiple FoV ToF imaging array may be used insystems with more than two cameras. The multiple FoV ToF imaging arraymay also be capable of being implemented with different camera modelshaving different FoV without having to modify the hardware of the ToFimaging array.

FIG. 3d shows circuit 432 for driving dual illumination source 406,according to an embodiment of the present invention. Circuit 432includes controller 438, switches 440 and 442 and VCSELs 444 and 446.

The anodes of VCSELs 444 and 446 may be connected to each other, and mayreceive power from a power supply at terminal V_(dd), such as a chargepump, linear regulator, or any other power source. Switches 440 and 442are respectively connected in series with VCSELs 444 and 446 and areconfigured to connect or disconnect the cathodes of the respectiveVCSELs to/from a reference voltage (e.g. ground).

During normal operation, a positive voltage is received at terminalV_(dd). When switch 440 is closed (e.g. on), VCSEL 444 generates light.When switch 440 is open (e.g. off), VCSEL 444 does not generate light.Similarly, when switch 442 is closed, VCSEL 446 generates light and whenswitch 442 is open, VCSEL 446 does not generate light.

Switches 440 and 442 may be controlled by controller 438 with signalsS₄₄₀ and S₄₄₂, respectively. For example, when signal S₄₄₀ is high,switch 440 is on, and when signal S₄₄₀ is low, switch 440 is off.Similarly, when signal S₄₄₂ is high, switch 442 is on, and when signalS₄₄₂ is low, switch 442 is off. It is understood that otherimplementations are also possible, such as, for example, by usingswitches and signals of opposite polarities, and/or by placing VCSELs444 and 446 between switches 440 and 442 and ground instead of betweenV_(dd) and switches 440 and 442.

Switches 440 and 442 may be implemented in any way known in the art. Forexample, switches 440 and 442 may be transistors of the n-type orp-type, such as metal-oxide-semiconductor field-effect transistors(MOSFETs), bipolar junction transistors (BJT), or any other transistortechnology. Alternatively, other switch implementations may be used,such as, for example, mechanical relays.

FIG. 3e shows a flow chart of embodiment method 452 of operating a dualcamera system, according to an embodiment of the present invention.Method 452 may be used to electrically reconfigure ToF imaging array 408to have a FoV equivalent to the FoV of a selected camera and use theoutput of ToF imaging array 408 to automatically focus the selectedcamera on the objects of interest. Method 408 may be implemented withdual camera system 400. Alternatively, method 408 may be implemented inother camera systems, such as, for example, a camera system having morethan two cameras. The discussion that follows assumes that dual camerasystem 400, as shown in FIGS. 3a-3d , implements method 452.

During step 454 a camera, such as a narrow FoV camera or a wide FoVcamera, is selected. During step 456, AF is launched. Depending on thecamera selected during step 454, a different VCSEL is activated and aToF imaging array, such as ToF imaging array 408, is reconfigured in adifferent way. For example, if it is determined during step 458 thatwide FoV camera is selected, the ToF imaging array is configured, duringstep 460, to have a wide FoV equivalent to the FoV of the selectedcamera and the wide light source, such as light source 421, is turned onaccording to ToF techniques during step 462.

Alternatively, if it is determined during step 458 that narrow FoVcamera is selected, the ToF imaging array is configured, during step464, to have a narrow FoV equivalent to the FoV of the selected cameraand the narrow light source, such as light source 423, is turned onaccording to ToF techniques during step 466. Any non-selectedphotodetector of the ToF imaging array may be turned off during step468. In some embodiments, step 466 may be replaced with step 462 becausean illumination source with a wide FoV may illuminate objects in thenarrow FoV.

The selected photodetectors of the ToF imaging array are used togenerate a distance histogram during step 470. Such histogram istransmitted to a controller or the AF module using the ToF channelsduring step 472. The controller or AF module receives the distancehistogram and performs AF of the selected camera based on the receiveddistance histogram during step 474. The AF may be performed, forexample, by controlling a lens driver to focus the lens of the selectedcamera. The light source that was turned on during either step 462 orstep 466 is turned off during step 476. The sequence may be repeated ifa different camera is selected, or AF is launched again.

It is understood that some of the steps shown in FIG. 3e may beperformed in a different order. For example, step 468 may be performedbefore step 462 or step 466. Steps 460 and 464 may be performed once acamera is selected n step 454 but before step 456 is executed.

A configurable ToF imaging array may be used in a system having morethan two illumination sources as well as in systems with a singleillumination source. For example, FIG. 4 shows a portion of dual camerasystem 500 having ToF module 503, which includes single illuminationmodule 504 and ToF sensor 402, according to an embodiment of the presentinvention. Dual camera system 500 is similar to dual camera system 400.Dual camera system 500, however, includes single illumination source 506and single TX lens 518 instead of dual illumination source 406 and dualTX lens 418. Single illumination source 506 includes light source 521.Single TX lens 518 includes wide FoV lens 520.

Dual camera system 500 operates in a similar manner than dual camerasystem 400. Dual camera system 500, however, uses the same illuminationsource 521 for AF regardless of which camera is selected. For example,dual camera system 500 may implement steps 454, 456, 458, 460, 462, 464,468, 470, 472, 474, and 476 of method 452, as shown in FIG. 3e . Step466, however, is replaced with step 462.

Advantages of some embodiments include avoiding having multipleillumination sources, which may increase the cost of the solution aswell as the size of the system. Even though when using the narrow FoVcamera with a wide FoV illumination source may result in illuminatingobjects that are not within the FoV of the narrow FoV camera, thedistance histograms generated by the ToF imaging array may not beimpacted. Any deficit in photon rate that may be caused by using a wideFoV illumination source may be compensated by increasing the intensityof the illumination source when narrow FoV camera is being used. Forexample, in a system implementing single illumination source 506 with aVCSEL, more current may be flown through the VCSEL up to a maximumcurrent when the narrow FoV camera is being used than when the wide FoVcamera is being used. The maximum current may be determined, forexample, based on a laser intensity safety threshold.

In some embodiments of the present invention, a camera system achieves aflat FoV by combining two light sources to illuminate objects with a ToFsensor having an electronically configurable array of photodetectors andhaving a dual TX lens including a diffractive optical element (DOE). Forexample, FIG. 5A shows a portion of dual camera system 600 having ToFmodule 603, which includes dual illumination module 604 and ToF sensor402, according to an embodiment of the present invention. Dual camerasystem 600 is similar to dual camera system 400. Dual camera system 600,however, includes dual TX lens 618 instead of dual TX lens 418. Dual TXlens 618 includes corner-weighted FoV lens 620 and center-weighted FoVlens 622. Even though lenses 620 and 622 have different weighting, theFoV of lenses 620 and 622 cover the same area, as shown by FoV 624 and626, respectively. The particular weighing of the lenses may beachieved, for example, using DOE.

FIG. 5b shows corner-weighted FoV 624, center-weighted FoV 626, andcombined, flat FoV 628 of dual TX lens 618, according to an embodimentof the present invention. FIG. 5b may be understood in view of FIG. 5a .As shown in FIGS. 5a and 5b , when light source 423 projects lightthrough center-weighted FoV lens 622, center-weight FoV 626 isilluminated. Center-weight FoV 626 has more energy at the center of theFoV than at the edges. Such FoV may be advantageous, for example, forperforming AF at long distances, where a ToF sensor may need moreoptical power in the center than in the edges. A flat FoV may beachieved by having both illumination sources 421 and 423 onsimultaneously, which results in flat FoV 628. Such flat FoV may beadvantageous for performing AF for all distances.

Dual camera system 600 may be used for performing AF in a system havinga first camera and a second camera, where the FoVs of both cameras arethe same. The first camera may be a color camera and the second cameramay be a black and white (B&W) camera. Other types of cameras may beused. It is understood that, in some embodiments, the FoVs of eachcamera of dual camera system 600 cameras may not be exactly the same forall conditions. For example, a discrepancy (e.g., misalignment) in FoVbetween each of the cameras of dual camera system 600 may exist forshort distances due to parallax. There may also be a discrepancy ormisalignments between FoV for long distances due to calibration issuedbetween each camera. By having a ToF sensor with configurable FoV, suchas ToF sensor 402, a correct FoV for capturing ToF information may beselected for each camera.

Dual camera system 600 may use both illumination sources 421 and 423simultaneously for short and mid-range AF (e.g., less than 2 m ofdistance), and may use illumination source 423 for performing longdistance AF (e.g., more than 2 m of distance). In some embodiments, whenoperating with illumination source 423 on and illumination source 421off, the array of photodetectors surrounded by perimeter 410 is selectedand used for ranging while photodetectors outside perimeter 410 are notselected.

In some embodiments, when operating with illumination source 423 on andillumination source 421 off, the intensity of light generated byillumination source 423 may be increased compared to when bothillumination sources 421 and 423 are on. The intensity of light may beincreased, for example, by increasing the current flowing through aVCSEL of illumination source 423.

FIGS. 6a and 6b show the front and back view, respectively, of mobilephone 700 including back-facing dual camera module 708 and ToF sensor714, according to an embodiment of the present invention. Mobile phone700 includes case 702, button interface 706, touchscreen 704, dualcamera module 708 and ToF sensor 714. Dual camera module 708 includesfirst camera 710 and second camera 712. ToF sensor 714 includes dual TXlens 716, dual VCSEL (not shown), RX lens 718 and ToF imaging array (notshown). Dual VCSEL is disposed behind dual TX lens 716, where each ofthe VCSELs of the dual VCSEL is configured to project light through eachof the TX lenses of dual TX lens 716. ToF imaging array is disposedbehind RX lens 718, where ToF imaging array is configured to receivelight coming through RX lens 718.

Mobile phone 700 may implement any of the embodiments described herein.For example, first camera 710 and second camera 712 may be implemented,for example, as a wide FoV camera and narrow FoV camera, respectively.In some embodiments, first camera 710 and second camera 712 may beimplemented as a color camera with a wide FoV and a B&W camera with awide FoV, where the FoV of the color camera and the B&W camera cover thesame area.

In some embodiments, ToF sensor 714 may be positioned between firstcamera 710 and second camera 712. Even though such arrangement mayincrease parallax between first camera 710 and second camera 712, itwould equalize parallax between ToF sensor 714 and first camera 710 andsecond camera 712.

It is understood that the physical arrangement of the cameras and ToFsensor in the phone may be different. For example, in some embodiments,the cameras and ToF sensor may be disposed in the front side of mobilephone 700. In other embodiments may arrange the order of the cameras, TXlenses and RX lens differently.

In some embodiments, a mobile phone may include a ToF sensor that isassociated with a front-facing camera. For example, FIG. 7 shows thefront view of mobile phone 800 including front-facing dual camera module808 and ToF sensor 814, according to an embodiment of the presentinvention. Dual camera module 808 and ToF sensor 814 may operate in asimilar camera than dual camera module 708 and ToF sensor 714.

It is understood that a mobile phone may include just a front-facingdual camera module 808 and ToF sensor 814, just a back-facing dualcamera module 708 and ToF sensor 714 or both. Other implementations arealso possible.

One general aspect includes a time of flight (ToF) sensor including: anillumination source module having a first vertical-cavitysurface-emitting laser (VCSEL); a transmitter (TX) lens module locatedbetween the illumination source module and a scene, the TX lens modulehaving a first TX lens, where the first VCSEL is configured to projectlight through the first TX lens; an integrated circuit (IC) including aToF imaging array configured to measure distances to objects in thescene, the ToF imaging array including a plurality of single photonavalanche diodes (SPAD), a plurality of ToF channels coupled to theplurality of SPADs, where: in a first mode, the ToF imaging array isconfigured to select a first group of SPADs from the plurality of SPADs,the first group of SPADs corresponding to a first field of view (FoV),the ToF imaging array also configured to measure distances to objects inthe scene corresponding to the first FoV, where the plurality of ToFchannels are configured to transmit ToF data corresponding to the firstFoV, and in a second mode, the ToF imaging array is configured to selecta second group of SPADs from the plurality of SPADs, the second group ofSPADs corresponding to a second FoV different than the first FoV, theToF imaging array also configured to measure distances to objects in thescene corresponding to the second FoV, where the plurality of ToFchannels are configured to transmit ToF data corresponding to the secondFoV; and a received (RX) lens located between the scene and the ToFimaging array.

Implementations may include one or more of the following features. TheToF sensor where the ToF imaging array is further configured to generatea depth map. The ToF sensor where the illumination source module furtherincludes a second VCSEL, where the TX lens module further includes asecond TX lens, and where the second VCSEL is configured to projectlight through the second TX lens. The ToF sensor where the first TX lenshas a wide FoV and the second TX lens has a narrow FoV. The ToF sensorwhere the first TX lens has a corner-weighted FoV and the second TX lenshas a center-weighted FoV. The ToF sensor where the first TX lensincludes a first diffractive optical element and the second TX lensincludes a second diffractive optical element. The ToF sensor where acombination of the corner-weighted FoV of the first TX lens with thecenter-weighted FoV of the second TX lens results in a flat FoV.

Another general aspect includes a system including: an illuminationsource module having a first illumination source; a transmitter (TX)lens module located between the illumination source module and a scene,the TX lens module having a first TX lens, where the first illuminationsource is configured to project light through the first TX lens; a timeof flight (ToF) imaging array configured to measure distances to objectsin the scene, the ToF imaging array including a plurality ofphotodetectors, a plurality of ToF channels coupled to the plurality ofphotodetectors, where: in a first mode, the ToF imaging array isconfigured to select a first group of photodetectors from the pluralityof photodetectors, the first group of photodetectors corresponding to afirst field of view (FoV), and measure distances to objects in the scenecorresponding to the first FoV, and the plurality of ToF channels areconfigured to transmit ToF data corresponding to the first FoV, and in asecond mode, the ToF imaging array is configured to select a secondgroup of photodetectors from the plurality of photodetectors, the secondgroup of photodetectors corresponding to a second FoV different than thefirst FoV, and measure distances to objects in the scene correspondingto the second FoV, and the plurality of ToF channels are configured totransmit ToF data corresponding to the second FoV; and a received (RX)lens located between the scene and the ToF imaging array.

Implementations may include one or more of the following features. Thesystem where, in the second mode, a group of unselected photodetectorsof the plurality of photodetectors is configured to be turned off beforethe ToF imaging array measures distances to objects in the scene, wherethe group of unselected photodetectors and the second group ofphotodetectors are mutually exclusive. The system where the first FoV isa wide FoV and the second FoV is a narrow FoV. The system where each ToFchannel is configured to transmit data associated with respective firstgroups of photodetectors when the ToF imaging array is in the firstmode, and where each ToF channel is configured to transmit dataassociated with respective second groups of photodetector when the ToFimaging array is in the second mode. The system where the respectivefirst groups of photodetectors include more than one photodetector andwhere the respective second groups of photodetectors include more thanone photodetector. The system where the respective second groups ofphotodetectors include one photodetector. The system where eachphotodetector includes a single photon avalanche diode (SPAD). Thesystem where the plurality of photodetectors are arranged in rows andcolumns on a semiconductor substrate of an integrated circuit (IC). Thesystem where the first illumination source includes a vertical-cavitysurface-emitting laser (VCSEL). The system further including a dualcamera module having a first camera and a second camera, where: theillumination source module further includes a second illuminationsource; and the TX lens module further includes a second TX lens, wherethe second illumination source is configured to project light throughthe second TX lens. The system where the TX lens module is locatedadjacent to lenses of the dual camera module and to the RX lens. Thesystem further including an autofocus (AF) module configured to receiveToF data from the ToF channels and to focus the dual camera module onobjects of the scene based on the received ToF data. The system wherethe first FoV corresponds to a FoV of the first camera, and the secondFoV corresponds to a FoV of the second camera. The system where thefirst TX lens has a wide FoV and the second TX lens has a narrow FoV.The system where the first TX lens has a corner-weighted FoV and thesecond TX lens has a center-weighted FoV. The system where the first TXlens includes a diffractive optical element (DoE) and the second TX lensincludes a DoE. The system where the system includes a mobile phone. Thesystem where the system includes an automotive light detection andranging (lidar) system.

Yet another general aspect includes a method including: at a first time,selecting a first camera of a dual camera system having the first cameraand a second camera, the first camera having a first field of view (FoV)and the second camera having a second FoV, projecting a first light froma first illumination source through a first transmitter (TX) lens,electrically configuring a time of flight (ToF) imaging array to have aFoV equivalent to the first FoV, capturing the first light with the ToFimaging array after the first light reflects from objects in the firstFoV, and transmitting ToF data associated with the captured first lightwith a plurality of ToF channels coupled to photodetectors of the ToFimaging array; and at a second time, selecting the second camera,projecting a second light from a second illumination source through asecond TX lens, electrically configuring the ToF imaging array to have aFoV equivalent to the second FoV, capturing the second light with theToF imaging array after the second light reflects from objects in thesecond FoV, and transmit ToF data associated with the captured secondlight with the plurality of ToF channels.

Implementations may include one or more of the following features. Themethod where the first camera has a wide FoV and the second camera has acenter-weighted FoV. The method where the first camera has acorner-weighted FoV and the second camera has a narrow FoV. The methodfurther including, at the second time: projecting the first light fromthe first illumination source through a first TX lens; and capturing thefirst light with the ToF imaging array after the first light reflectsfrom objects in the first FoV, where the transmitted ToF datacorresponds to a flat FoV. The method where projecting the first lightfrom the first illumination source through the first TX lens includesturning on a first vertical-cavity surface-emitting laser (VCSEL). Themethod further including: receiving, with an autofocus (AF) module, ToFdata captured with the ToF imaging array; and adjust a lens of the dualcamera system with the AF module based on the ToF data received by theAF module.

Another general aspect includes a mobile phone including: a dual cameramodule having a first camera and a second camera, where the first camerahas a first field of view (FoV) and the second camera has a second FoV;a dual illumination source having a first light source and a secondlight source; a dual transmitter (TX) lens located between the dualillumination source and a scene, the dual TX lens including a first TXlens and a second TX lens, where the first light source is configured toproject light through the first TX lens, and the second light source isconfigured to project light through the second TX lens; a time of flight(ToF) imaging array configured to measure distances to objects in thescene, the ToF imaging array including a plurality of photodetectors, aplurality of ToF channels coupled to the plurality of photodetectors,where: in a first mode, the ToF imaging array is configured to select afirst group of photodetectors from the plurality of photodetectors, thefirst group of photodetectors corresponding to the first FoV, andmeasure distances to objects in the scene corresponding to the firstFoV, and the plurality of ToF channels are configured to transmit ToFdata corresponding to the first FoV, and in a second mode, the ToFimaging array is configured to select a second group of photodetectorsfrom the plurality of photodetectors, the second group of photodetectorscorresponding to the second FoV different than the first FoV, andmeasure distances to objects in the scene corresponding to the secondFoV, and the plurality of ToF channels are configured to transmit ToFdata corresponding to the second FoV; a received (RX) lens locatedbetween the scene and the ToF imaging array; and an au ToF ocus (AF)module configured to receive ToF data from the ToF channels and to focusthe dual camera module on objects of the scene based on the received ToFdata.

Implementations may include one or more of the following features. Themobile phone where the dual camera module and the ToF imaging array arelocated in a back cover of the mobile phone. The mobile phone furtherincluding: a second dual camera module located in a front cover of themobile phone; and a second ToF imaging array located in the front coverof the mobile phone.

While this invention has been described with reference to illustrativeembodiments, this description is not intended to be construed in alimiting sense. Various modifications and combinations of theillustrative embodiments, as well as other embodiments of the invention,will be apparent to persons skilled in the art upon reference to thedescription. It is therefore intended that the appended claims encompassany such modifications or embodiments.

What is claimed is:
 1. A time of flight (ToF) sensor comprising: anillumination source configured to project light towards a scene; and aToF imaging array configured to measure distances to objects in thescene, the ToF imaging array comprising: a plurality of photodetectors,and a plurality of ToF channels coupled to the plurality ofphotodetectors, wherein: in a first mode, the ToF imaging array isconfigured to select a first group of photodetectors from the pluralityof photodetectors, the first group of photodetectors corresponding to afirst field of view (FoV), the ToF imaging array also configured tomeasure distances to objects in the scene corresponding to the firstFoV, wherein the plurality of ToF channels are configured to transmitToF data corresponding to the first FoV, and in a second mode, the ToFimaging array is configured to select a second group of photodetectorsfrom the plurality of photodetectors, the second group of photodetectorsbeing different than the first group of photodetectors, the second groupof photodetectors corresponding to a second FoV having different sizethan the first FoV, the ToF imaging array configured to measuredistances to objects in the scene corresponding to the second FoV,wherein the ToF imaging array is configured to turn off a third group ofunselected photodetectors of the plurality of photodetectors before theToF imaging array measures distances to objects in the scenecorresponding to the second FoV, and wherein the plurality of ToFchannels are configured to transmit ToF data corresponding to the secondFoV.
 2. The ToF sensor of claim 1, wherein the illumination sourcecomprises a vertical-cavity surface-emitting laser (VCSEL).
 3. The ToFsensor of claim 1, further comprising a TX lens, wherein theillumination source is configured to project the light through the TXlens.
 4. The ToF sensor of claim 1, further comprising a receiver (RX)lens, wherein the ToF imaging array is configured to receive photonsthrough the RX lens.
 5. The ToF sensor of claim 1, wherein the ToFimaging array is further configured to generate a depth map.
 6. The ToFsensor of claim 1, wherein the plurality of photodetectors is aplurality of single photon avalanche diodes (SPADs).
 7. The ToF sensorof claim 1, wherein the plurality of photodetectors and the illuminationsource are integrated in the same integrated circuit.
 8. The ToF sensorof claim 1, wherein, in a third mode, the ToF imaging array isconfigured to select a fourth group of photodetectors from the pluralityof photodetectors, the fourth group of photodetectors corresponding to athird FoV, the ToF imaging array configured to measure distances toobjects in the scene corresponding to the third FoV, wherein theplurality of ToF channels are configured to transmit ToF datacorresponding to the third FoV, wherein the third FoV is different thanthe first FoV and the second FoV.
 9. A mobile device comprising: a firstcamera having a first field of view (FoV); a second camera having asecond FoV; a first light source configured to project light towards ascene; a second light source configured to project light towards thescene; a first transmitter (TX) lens, wherein the first light source isconfigured to project light through the first TX lens; a secondtransmitter TX lens, wherein the second light source is configured toproject light through the second TX lens; a time of flight (ToF) imagingarray configured to measure distances to objects in the scene, the ToFimaging array comprising: a plurality of photodetectors, and a pluralityof ToF channels coupled to the plurality of photodetectors, wherein: ina first mode, the ToF imaging array is configured to select a firstgroup of photodetectors from the plurality of photodetectors, the firstgroup of photodetectors corresponding to the first FoV, and measuredistances to objects in the scene corresponding to the first FoV,wherein the plurality of ToF channels are configured to transmit ToFdata corresponding to the first FoV, and in a second mode, the ToFimaging array is configured to select a second group of photodetectorsfrom the plurality of photodetectors, the second group of photodetectorsbeing different than the first group of photodetectors and correspondingto the second FoV having a different size than the first FoV, andmeasure distances to objects in the scene corresponding to the secondFoV, wherein the ToF imaging array is configured to turn off a thirdgroup of unselected photodetectors of the plurality of photodetectorsbefore the ToF imaging array measures distances to objects in the scenecorresponding to the second FoV, and wherein the plurality of ToFchannels are configured to transmit ToF data corresponding to the secondFoV; and a receiver (RX) lens, wherein the ToF imaging array isconfigured to receive photons through the RX lens.
 10. The mobile deviceof claim 9, wherein the mobile device is a mobile phone.
 11. The mobiledevice of claim 10, wherein the mobile phone comprises a touchscreen ata first surface of the mobile phone, and wherein the first and secondcameras are disposed at the first surface.
 12. The mobile device ofclaim 9, wherein the first and second light sources, the first andsecond TX lenses, the RX lens, and the ToF imaging array form a ToFsensor disposed between the first and second cameras.
 13. The mobiledevice of claim 9, further comprising an autofocus (AF) moduleconfigured to receive ToF data from the ToF channels and to focus thefirst camera or the second camera on objects of the scene based on thereceived ToF data.
 14. The mobile device of claim 9, wherein the firstcamera is a color camera and the second camera is a black and whitecamera.
 15. The mobile device of claim 9, wherein the first TX lens hasa first TX FoV that has more energy at edges of the first TX FoV than ata center of the first TX FoV, and wherein the second TX lens has asecond TX FoV that has more energy at a center of second TX FoV than atedges of the second TX FoV.
 16. A device comprising: a dual camerasystem comprising a first camera having a first field of view (FoV), anda second camera having a second FoV; a transmitter (TX) lens; anillumination source configured to project light through the TX lens; areceiver (RX) lens configured to receive reflected photons originatingfrom the illumination source; and a time of flight (ToF) imaging arrayconfigured to receive the reflected photons via the RX lens, the ToFimaging array comprising: a plurality of photodetectors occupying afirst area surrounded by a first perimeter, and a plurality of ToFchannels coupled to the plurality of photodetectors, wherein: in a firstmode, the ToF imaging array is configured to activate the illuminationsource with a first intensity, and select a first group ofphotodetectors from the plurality of photodetectors, the first group ofphotodetectors occupying the first area and corresponding to the firstFoV, wherein the plurality of ToF channels are configured to transmitToF data corresponding to the first FoV, and in a second mode, the ToFimaging array is configured to activate the illumination source with asecond intensity and to select a second group of photodetectors from theplurality of photodetectors, the second group of photodetectorsoccupying a second area smaller than the first area, the second areabeing surrounded by a second perimeter that is within the firstperimeter, wherein the second intensity is higher than the firstintensity, and wherein the plurality of ToF channels are configured totransmit ToF data corresponding to the second FoV.
 17. The device ofclaim 16, wherein, in the second mode, the ToF imaging array isconfigured to turn off a third group of photodetectors of the pluralityof photodetectors, the third group of photodetectors occupying a thirdarea located between the second perimeter and the first perimeter. 18.The device of claim 16, wherein the ToF data comprises a distancehistogram.
 19. The device of claim 16, wherein the plurality ofphotodetectors comprises a plurality of single photon avalanche diodes(SPADs).
 20. The device of claim 16, wherein the illumination sourcecomprises vertical cavity surface emitting laser (VCSEL), the devicefurther comprising an autofocus (AF) module configured to receive ToFdata from the ToF channels and to focus the first camera or the secondcamera based on the received ToF data, wherein the ToF imaging array isconfigured to turn off the VCSEL after the AF modules focuses the firstcamera or the second camera.